Dynamoelectric machines such as motors and generators are widely employed in industrial and commercial facilities. These machines are relied upon for prolonged consistent operation, with only minimal attention. However, as with most machinery, at least a small percentage of such motors are prone to failure. The majority of the failures can be attributed to mechanical failures and/or thermal failures of the machine insulation. Other than normal aging, failures are typically due to poor maintenance, inappropriate insulation (e.g., wrong enclosure, excessive loading, etc.) and/or improper installation (e.g., misalignment, bad power, inverter mismatch, etc.). Moreover, even with normal aging failures, it is desirable to provide reliable failure prediction information for such machines.
The failure of a machine in service can lead to system down time, inconvenience, and possibly even hazardous conditions. Thus, it desirable to diagnose the machinery for possible failure or faults early in order to avoid such problems. Certain motor problems have an insidious effect in that although only a minor problem at the onset, they become serious if not detected. For example, insulation problems and electrical problems may not become apparent until irreversible damage is done. Likewise, bearing problems due to inadequate lubrication, contamination or other causes sometimes are only recognized after irreparable destruction has occurred.
Machine preventive maintenance is typically performed by coupling one or more portable recorders to a machine to collect data relevant to the machine's health, such as vibration data, motor flux data, motor current data and/or motor temperature data. Many such portable recorders experience problems with consistency in data recovery because of the inherent difficulty associated with placing the portable recorder in the exact same position as when the previous recording was taken. Since the creditableness of any trend analysis rests on the ability to reproduce the precise location of the data sensed so that accurate comparisons may be made, portable recorders are usually deficient in obtaining reliable data. Furthermore, because monitoring typically takes place at the machine, diagnosis may require significant manpower to collect the data.
Accordingly, the inventor appreciated that a need remains for an integrated dynamoelectric machine diagnostic system which measures vibration, current, temperature, voltage, shaft position and other parameters relating to the health of the machine. The inventor further appreciated that in such a diagnostic system, it would be preferable (if not necessary) for the component performing these measurements to be permanently mounted to the machine while at the same time being protected against environmental contamination and thermal damage.